A lot of hair dyes are constituted from two types of preparations called a first preparation (to be referred sometimes to as “hair dye first preparation” hereinafter) and a second preparation (to be referred sometimes to as “hair dye second preparation” hereinafter). The first preparation contains dye intermediates including, e.g., an alkaline agent such as ammonia or an alkanolamine and a surfactant, and the second preparation contains, e.g., an oxidizing agent such as hydrogen peroxide and a pH adjusting agent. The main role of the first preparation is to effect penetration of the dye intermediates and oxidizing agent into hair through swelling of hair by the alkaline agent, and the main role of the second preparation is to remove melanin pigment from hair, develop a color through mutual binding of molecules of the dye intermediates and thereby fix the pigment into hair.
Various types of deodorant compositions for hair dyes have been examined in order to mask malodors originated from the malodors such as of ammonia or the alkanolamine formulated in the first preparation. However, since the first preparation generally shows an alkalinity of from pH 8 to 11 due to large amount of the formulated ammonia, it is required that a fragrance to be formulated has a property of being stable to the alkaline nature.
To date, stability and masking effect of various types of fragrance components have been examined, and deodorant compositions containing specified fragrance have been reported. For example, a method for masking an ammoniacal malodor or a solvent malodor of an aromatic alcohol by using a hair dye treatment composition containing cis-3-hexenol as a fragrance is disclosed (Patent Document 1). Further, methods in which specified fragrances are used are also disclosed (Patent Documents 2 to 6). These methods in which the above-described fragrances such as cis-3-hexenol are merely used can improve the malodor at the time of filling a hair dye product in a container. However, these methods have problems in that, after such filling, the masking effect becomes weak and cannot be exerted for a long period of time due to the change of the odor quality, and further, after the treatment, the masking effect becomes weak due to the weakness of the retention property of odor. Therefore, these methods cannot be regarded to be fully satisfied.
On the other hand, a dye component in hair dye base materials is high in reactivity, and therefore, there has been an inconvenience that, even at a stage in which the hair dye is stored before it is applied to hair, a polymerization occurs in the presence of oxygen in the air and thereby color is developed. Accordingly, various types of improvements for solving the above inconvenience have so far been made.
As one method, there may be mentioned a method in which the hair dye is blocked from air. Namely, an improvement has been made such that the hair dye is produced or allowed to be a commercial product in an atmosphere in which the hair dye is hardly in contact with oxygen by removing oxygen dissolved in a base material or by purging a container to which the base materials are stored with an inert gas which does not cause a reaction or the like. For example, in Patent Document 7, it is described that a mixing operation of components constituting a hair dye composition is conducted in an atmosphere in which an oxygen concentration is 0.00015% or less. However, in order to perform such an operation as described above, there is a problem in that economical burden is large. Furthermore, since highly-reactive dye compounds are apt to be degenerated and hair dying effect comes to be deteriorated along a passage of time, it is necessary to pay a great effort for keeping a value as a commercial product.
As another method, there may be mentioned a method of using a medicament. Namely, there is a method in which a given type of reducing agent, for example, a sulfite, vitamin C (ascorbic acid and salts thereof) or the like is added to the base materials and an active species generated in the base materials is trapped for preventing a deterioration of a hair dyeing effect over time by preventing a degeneration or the like of a highly-reactive dye compound (for example, Patent Documents 8 and 9). Although the above method is effective to a given extent, when an amount of the medicament to be used is large, for example, when it is more than 1% by weight, the dye is subjected to a reducing action to cause a problem in color development or an irritation to the skin, which is not preferred (for example, Patent Document 10). Moreover, since some of medicaments to be used have high penetrability into hair and are likely to cut a keratin protein through the reduction reaction, there is a fear that decrease of hair strength arises (Patent Document 11).
Still further, a method in which stabilization is realized by suppressing bonding or reaction between dye molecules by the addition of a surfactant is disclosed (for example, Patent Document 10). However, the effect of stability is not sufficient.
Patent Documents cited herein are as follows.
Patent Document 1: JP-A-2002-97122
Patent Document 2: JP-A-2000-344629
Patent Document 3: JP-A-2003-137758
Patent Document 4: JP-A-2003-277246
Patent Document 5: JP-A-2003-321697
Patent Document 6: JP-A-2004-107208
Patent Document 7: JP-A-2000-344638
Patent Document 8: JP-A-9-136818
Patent Document 9: JP-A-7-309732
Patent Document 10: JP-A-7-82121
Patent Document 11: JP-A-9-315948